Many speak english (except, for some reason, those at the immigration desk). Other stuff can be done online, in English. If people are really nervous, they usually find someone to come along and translate, or they meet someone in the waiting room.

To be honest, those things can be pretty involved here even for me as German, so it probably makes sense to just use someone who does that as a service (obvious for taxes, but most likely also available for business registration etc) rather than investing your time in understand bureaucratic German.